Morphological and molecular description of a novel species of Eimeria (Apicomplexa) that infects extraintestinal tissues of kiwi (Aves: Apteryx spp.)

Syst Parasitol (2025) 102:30 https://doi.org/10.1007/s11230-025-10227-x Morphological and molecular description of a novel species of Eimeria (Apicomplexa) that infects extraintestinal tissues of kiwi (Aves: Apteryx spp.) Emma Scheltema Laryssa Howe · Kerri Morgan · Preet Singh · Barbara Adlington · Received: 31 January 2025 / Accepted: 23 March 2025 / Published online: 9 April 2025 © The Author(s) 2025, Corrected publication 2025 Abstract Coccidia (Apiconmplexa) are naturally occurring and occasionally detrimental parasites of kiwi (Apteryx spp.), a unique, flightless bird species dependent upon conservation efforts for survival. Using morphological and molecular data, a new coccidia species, Eimeria koka n. sp., isolated from two closely related but geographically isolated kiwi host species, Apteryx rowi Tennyson et al. (rowi) and Apteryx mantelli Bartlett (North Island brown kiwi), is described. Oocysts are oval (20.8 × 15.9 μm) with a mean L/W ratio of 1.3, and a distinctive rough, crenellated brown oocyst wall (mean 1.2 μm), an oocyst residuum, 1–2 polar granules, and no micropyle. Sporocysts are ellipsoidal (11.6 × 6.3 μm) with a Stieda body and sporocyst residuum. Phylogenetic analysis of the cytochrome C oxidase subunit 1 (CO1) placed E. koka n. sp. in a separate clade to other Eimeria species previously identified from kiwi (Coker et al., Syst Parasitol 100(3):269–281, 2023). Comparison of DNA from oocysts with infected tissues from a single Supplementary Information The online version contains supplementary material available at https://doi. org/10.1007/s11230-025-10227-x. E. Scheltema (*) · P. Singh · B. Adlington · L. Howe School of Veterinary Sciences, Massey University, Palmerston North, New Zealand e-mail: K. Morgan Wildbase, Massey University, Palmerston North, New Zealand juvenile North Island brown kiwi confirmed parasitism of the kidney and lung tissues. This is the first Eimeria species identified from extraintestinal tissues in kiwi. Further molecular studies are recommended to determine the tissue distribution of E. koka n. sp. and other Eimeria species in kiwi. Introduction Kiwi, the smallest extant species of ratite, are nocturnal, flightless ground-dwelling birds with an unusual burrow-nesting behaviour (Calder, 1978; Taborsky & Taborsky, 1995; Sales, 2005; Peat, 2006). There are five recognised species of kiwi (Apterygiformes: Apterygidae) in two morphological groups, all endemic to New Zealand: brown kiwi consisting of North Island brown kiwi (Apteryx mantelli Bartlett), rowi (Apteryx rowi Tennyson et al.), and tokoeka (Apteryx australis Shaw), and spotted kiwi consisting of little-spotted (Apteryx owenii Gould) and greatspotted kiwi (Apteryx haastii Potts) (Burbidge et al., 2003; Shepherd et al., 2012). Kiwi populations have declined dramatically over the last century as a result of escalating anthropogenic impacts upon the natural environment, including habitat modification and successive introductions of mammalian predators (McLennan et al., 1996, 2004). Since the early 1990s, with the launch of the Kiwi Recovery Plan, there has been a significant investment in conservation interventions, such Vol.: (0123456789) 30 Page 2 of 20 as captive-rearing (Operation Nest Egg or ONE), to maintain and, in some cases, increase kiwi populations (Butler & McLennan, 1991; Colbourne et al., 2005; Robertson et al., 2011; Germano et al., 2018). However, Coccidia (Apicomplexa), which are ubiquitous in captive and wild kiwi populations, are considered a major limiting factor in the success of captiverearing programmes, causing morbidity and mortality in juvenile captive birds (Boardman, 2008; Morgan et al., 2014). Coccidiosis in kiwi was first recorded in a 19-dayold captive-reared brown kiwi chick suffering from renal infection in 1978 (Thompson & Wright, 1978). Four coccidia morphotypes were reported from faeces of other kiwi chicks from the same facility, but they were unable to be sporulated or further described (Thompson & Wright, 1978). The first in-depth epidemiological, morphological, and molecular study of coccidia in kiwi was carried out by Morgan (2013). This study included a thorough analysis of sporulated oocysts from North Island brown kiwi, and the author was able to confirm that the species of coccidia routinely recovered from kiwi were of the genus Eimeria. Further, Morgan described four distinct species; Eimeria apteryxii (Morgan et al., 2017), E. kiwii (Morgan et al., 2017), E. paraurii (Morgan et al., 2017), and E. mantellii (Morgan et al., 2017) from North Island brown kiwi. Subsequently, one additional species from North Island brown kiwi, Eimeria paopaoii (Coker et al., 2023), has been described. Infection with multiple species of Eimeria is common in kiwi, and while infection typically occurs in the intestine, it occasionally occurs in extraintestinal tissues, including the kidney, liver, lungs, and spleen (Morgan et al., 2012, 2013). However, which Eimeria species cause these differing disease pathologies is currently unknown. These previous studies have described coccidia recovered from a relatively small number of individual North Island brown kiwi from a limited number of geographic locations. Although most Eimeria species are highly host specific, recent research shows that some have a wider host spectrum than traditionally thought; several Eimeria species are shared across multiple host genera or family groups (Duszynski & Wilber, 1997; Mácová et al., 2018; Kvičerová et al., 2020; Trefancová et al., 2021). Coker (2021) Vol:. (1234567890) Syst Parasitol (2025) 102:30 reported Eimeria species from Haast tokoeka (A. australis “Haast”) that were morphologically synonymous with four of the species described to date from North Island brown kiwi. Given that there has been limited investigation of coccidia infecting other species of kiwi across a variety of geographic locations, it is possible that more kiwi Eimeria species have yet to be identified and described. In addition, translocations of kiwi for the purposes of conservation inadvertently bring together hosts and parasites that are normally geographically isolated, and may have facilitated parasite transmission between members of the genus Apteryx (Morgan et al., 2017; Coker, 2021; Jahn et al., 2022). In the present study, a morphologically distinct species of Eimeria recovered from both rowi and North Island brown kiwi, from multiple geographic locations around New Zealand, is described. Establishing basic biology and taxonomy of Eimeria species in kiwi is a fundamental step in developing tools to detect and manage disease. Materials and methods Morphological analysis Faecal sample collection and storage Coccidia-positive faecal samples were received from routine diagnostic screening of kiwi carried out at Massey University’s Parasitology Department (Massey University, Manawatū, New Zealand). Samples were submitted from captive and creche (protected wild) location (...truncated)